Ports on printer configuration on Windows XP disappeared!

If anyone has found a solutions for this kind of problem I will appreciate your help on this. I have a Windows XP based PC that from time to time when you try to print something it doesnt and if you take a look at the printer configuration you see that the list of ports are disappeared, and you give the machine a RESTART to see if that solves the problem but it still remains hidding the ports on the printer configuration. I have scanned the machine for virus, spywares and haven’t found none, have updated Windows XP via internet and nothing. If someone has have this problem and found a solution I will appreciate if can share it with me. Thanks.